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Hydraulic Single-Acting Spring Return Actuators (HSA)

Simplified Fail-Safe Operation

The Master Flo HSA Actuator blends the robustness of hydraulic piston technology with a spring-return mechanism, mirroring the fail-safe functionality found in pneumatic systems. This innovative design ensures reliability through simplified fail-safe operations, even in the absence of hydraulic supply pressure. Ideal for applications demanding uncompromised safety and efficiency, the HSA Actuator represents a significant advancement in hydraulic control systems, providing a streamlined solution to traditional hydraulic actuation challenges.

Hydraulic Single-Acting (HSA), Spring Return Actuator
  • Hydraulic Piston Technology: Incorporates Master Flo’s proven hydraulic piston actuator for robust performance.
  • Spring-Return Mechanism: Adds the flexibility and reliability of spring-return action for fail-safe operation.
  • Simplified Fail-Safe: Ensures operation continuity even with the loss of hydraulic supply, offering a simplified approach to fail-safe mechanisms compared to traditional systems.
  • Enhanced Safety: Designed to provide an additional layer of operational safety across various applications.
  • Flexibility in Use: Suitable for a wide range of applications requiring precise control and reliability.

Fail Action

  • Spring Fail Close
  • Spring Fail Open
  • Fail Last

Control Signal (with control system)

  • 4–20 mA
  • HART
  • Fieldbus

Feedback Signal (positioner dependent)

  • 4–20 mA
  • HART
  • Fieldbus

Maximum Supply Pressure

  • 1500 psig

Hazardous Area Certification

  • CSA/FM/UL: Explosion Proof or Intrinsically Safe,
  • ATEX/IEC: Intrinsically Safe or Flameproof


  • Solenoid Valves
  • Position Controller
  • Handpump Override

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